This invention relates to an apparatus for successively processing a plurality of sheet-like substrates by sputtering, vapor evaporation, ion implantation, or the like processing procedure and, in particular, to a processing apparatus comprising a couple of cassette members for holding the substrates.
As will later be described with reference to one of several figures of the accompanying drawing, a conventional processing apparatus comprises a processing chamber for actually processing each of sheet-like substrates in a processing hollow space defined by the processing chamber. Each of the substrates is transferred from an inlet chamber to an outlet chamber through the processing chamber before and after processed in the processing hollow space. A first cassette member is accommodated in the inlet chamber so as to hold a stack of unprocessed substrates. A second cassette member is accommodated in the outlet chamber so as to hold a stack of processed substrates. The substrates may be those for use in manufacturing semiconductor integrated circuits.
A pressure in the inlet chamber should be changed from the atmospheric pressure to a reduced pressure at the beginning of processing procedure with the unprocessed substrates held in the first cassette member while a pressure in the outlet chamber should be changed from a low pressure to the atmospheric pressure at the completion of the processing procedure with the processed substrate kept in the second cassette member. Therefore, air flow takes place from the inlet chamber and out of the outlet chamber at the beginning and the completion of the processing procedure with the substrates placed in the respective chambers.
The air flow sprinkles dust in the inlet and the outlet chambers. Such dust is liable to attach or deposit onto the unprocessed and the processed substrates to bring about pin holes in a semiconductor integrated circuit manufactured by the use of the processing apparatus.
Deposition of dust is inevitable with the conventional processing apparatus comprising the cassette members, as will later be described. In addition, each of substrates is placed for a long time in either the inlet chamber or the outlet chamber until all substrates are processed in the processing apparatus. Possibility of the deposition of dust is enhanced more and more.